Horridon 25man Heroic Advice

My guild is going to begin to progress on this boss soon and i need to ask the community about something.
I am planning to play Demo for this fight. And dont go oh but you should play Destro because it is the best specc for this fight. I know that but i cant play destro at all and affliction isnt that good for that fight imo so i took the specc i feel somewhat decent at..
How should i play this fight as a demolock?
Just use Hellfire on all mobs? Or should i dot them up with corruption and then go into meta and use hellfire and maybe put up some dooms?
If anyone have any tips for this situation it will be much apprechiated and it will help me out aswell.